The Softpedia editors just published an extensive Mailplane review. Mailplane got a VERY GOOD (4 out of 5 stars)!

Mailplane is a friendly piece of software that aims to enhance and optimize the way you write and manage e-mails. It lets you add new buttons in the Toolbar and play with the shortcuts, so that you can switch views, convert attachments or minimize pictures within a click. Mailplane provides you with a different approach for labeling more e-mails at a time and a good search method.